OAKLAND, Calif. (AP) -- California Gov. Jerry Brown's office has asked that two of San Francisco Bay Area Rapid Transit's largest unions and management return to the bargaining table as a possible strike looms.

Marty Morgenstern, Brown's secretary of the Labor and Workforce Development Agency, requested that talks continue between Service Employees International Union Local 1021, Amalgamated Transit Union Local 1555 and BART representatives, Brown spokesman Evan Westrup said Sunday.

Westrup added that the governor will not call for a "cooling off period" and state mediators will continue assisting the negotiating parties as the unions' contracts are set to expire at midnight.

"BART and its labor unions owe the public a swift resolution of their differences," Westrup said. "All parties should be at the table doing their best to find common ground."

Both unions were scheduled to meet at noon Sunday to discuss their next steps, an SEIU spokeswoman said, one day after union negotiators said they would likely strike, which would cripple the region's Monday morning commute.

BART spokesman Rick Rice said the transit agency had scheduled a 1 p.m. Sunday meeting with the unions with hopes talks will continue.

As the deadline nears, both sides said Sunday they were far apart on key sticking points including salary, pensions, health care and safety as anticipated around-the-clock negotiations fell apart as the unions packed up and left after talks stalled Saturday afternoon.

The unions want a 5 percent annual raise over the next three years. BART said Saturday that train operators and station agents in the unions average about $71,000 in base salary and $11,000 in overtime annually. The workers also pay a flat $92 monthly fee for health insurance.

Rice said BART's latest proposal offered an 8 percent salary raise over the next four years, instead of its original offer of 4 percent. The proposed salary increase is on top of a 1 percent raise employees were scheduled to receive Monday, Rice added.

The transit agency also said it offered to reduce the contribution employees would have to make to their pensions, and lower the costs of health care premiums they would have to pay.

But ATU Local President Antonette Bryant said Sunday that BART's latest proposal is not an actual pay increase, calling it "surface bargaining."

"They are not straight across-the-board raises. They haven't provided us with the information that we need, numbers on the budget are bouncing all over the place, they change almost daily," Bryant said. "We can't bargain with incorrect or misinformation."

Josie Mooney, an SEIU chief negotiator, said Saturday after talks stalled that there was "a 95 percent chance" that her union and the ATU would strike.

"I'm afraid I don't see a way we will avoid a strike," Mooney said, claiming that the unions have met with BART's management for only 10 minutes in the past 36 hours.

The two unions, which represent nearly 2,400 train operators, station agents, mechanics, maintenance workers and professional staff, had no plans to meet with BART on Sunday.

But, with a walkout that could derail the more than 400,000 riders who use the nation's fifth-largest rail system and affect every mode of transportation, clogging highways and bridges throughout the Bay Area, the governor's office request may salvage talks.

Rice said Sunday that BART's latest proposal may not be its best last offer.

"We need to have some substantial discussions," Rice said. "I hope we can make some progress."

BART's last strike lasted six days in 1997. On Friday, other area transit agencies urged commuters to consider carpooling, taking buses or ferries, working from home and, if they must drive to work, to leave earlier or even later than usual.

A strike would be "an absolute nightmare," said Jim Wunderman, president and CEO of the Bay Area Council, a business advocacy organization.

"Our transportation system simply does not have the capacity to absorb the more than 400,000 BART riders who will be left at the station," Wunderman said Saturday. "There will be serious pain."